FR2513256A1 - ELASTOMER SEPARATOR ELEMENT, PROCESS FOR PREPARING THE SAME AND USE THEREOF IN HYDROPNEUMATIC SUSPENSION SYSTEMS - Google Patents

Abstract

THE OBJECT OF THE INVENTION IS AN ELASTOMERIC SEPARATOR ELEMENT, ITS PREPARATION PROCESS AND ITS USE IN HYDROPNEUMATIC SUSPENSION SYSTEMS. THIS ELEMENT INCLUDES AN ELASTOMER MEMBRANE GRAFT BY MONOINSATURE AND OR POLYUNSATURE MONOMERS CHOSEN FROM THE GROUP INCLUDING ACRYLIC ACID AND ITS ESTERS, ETHYLENE GLYCOL ACRYLATE, ACRYLONITRILE, VINYRATELONITRILE, VINYRONE, STACRYLEPYLPYRAN DIOL, DIETHYLENE GLYCOL DIACRYLATE, TETRAETHYLENE GLYCOL DIACRYLATE AND POLYETHYLENE GLYCOL DIACRYLATE. IT IS OBTAINED BY IMPREGNING A MEMBRANE WITH ELASTOMER, FOR EXAMPLE POLYURETHANE, MONOMERS SUCH AS ACRYLONITRILE AND THEN SUBJECTING TO IRRADIATION BY MEANS OF IONIZING RADIATION OF THE IMPREGNATED MEMBRANE.

Description

The subject of the invention is a separate element

  elastomer, intended in particular to ensure the

  paration between a liquid phase and a gas phase.

  It also aims at the process of

  this element and its applications. We already know elements of the kind in

  question; they come in the form of membra-

  polyurethane and find use in

  the field of "hydropneumatic suspension systems

  motor vehicles, in which they separate a liquid phase from a gaseous phase, and must therefore have a permeability to gases

the weakest possible.

  The known separators have a

  gas meableness which is already weak; a further decrease in this permeability is however

  desired, especially when the pressures and temperatures

  encountered in hydropneumatic systems

concerned increase.

  Research in this direction has not

  until today been successful.

  The object of the invention is therefore to provide

  separating elements of the kind in question whose

  gas mea- surement is even lower than that of

  elements that already exist and whose properties

  in particular the constraints for an extension

  given, remain compatible with the applica-

envisaged.

  For this purpose, the separating element according to the invention is characterized in that it comprises a

  elastomer membrane grafted with monomers monoin-

  saturated and / or polyunsaturated selected from the group consisting of acrylic acid and its esters, acrylate

  ethylene glycol, acrylonitrile, vinylpyrrolidine

  therefore, styrene, hexane diol diacrylate, dia-

  diethylene glycol crylate, the tetra-diacrylate

  ethylene glycol and polyethylene glycol diacrylate

  collar. According to the invention, the elastomer is

  chosen from the group comprising the poly-

  urethanes, polychloroprenes, silicones,

  ethylene-acrylic polymers such as copolymers

  ethylene and methyl acrylate, polyiso-

  butylenes, polynorbornenes, polybutadiene

  acrylonitriles, polybutadiene-styrenes, poly-

  butadienes, polyisobutylene-isoprenes, poly-

  isoprenes, chlorosulfonated polyethylenes, poly

  (ethylene-propylene), poly (ethylene-propylene-

  diene) and ethylene polysulfides.

  In the separator element of the invention, the fact of using an elastomer membrane grafted with monounsaturated and / or polyunsaturated monomers makes it possible to obtain a gas permeability lower than that of ungrafted elastomer membranes,

  while retaining mechanical properties, particularly

  elastic properties, acceptable.

  Indeed, when the grafted monomer is a polyunsaturated monomer, a reduction in

  permeability by tightening the macromolecular network

  the elastomer because of its crosslinking;

  when the grafted monomer is a monounsaturated monomer

  d, this decrease in permeability comes mainly from a clogging of the pores of the elastomeric membrane by the grafts. Thus, the reduction of permeability

  of the membrane depends mainly on the rate of mono-

grafted mothers on the elastomer.

  Advantageously, this rate is from 2 to 30% by

  weight relative to the weight of elastomer.

  Moreover, the fact of using according to

  the monomers mentioned above as monomers

  This decreases the permeability without reducing the mechanical properties of the elastomer, in particular its elastic properties. The choice of the monomer used also influences the

permeability.

  According to the invention, when the elastomer is a polyurethane, the grafted monomer is preferably acrylonitrile.

  The invention also relates to a method

  preparation die of an elastomeric separating element

  meet the above characteristics.

  This process is characterized by the fact that

  has an elastomer membrane of monomers

  saturated and / or polyunsaturated selected from the group consisting of acrylic acid and its esters, acrylate

  ethylene glycol, acrylonitrile, vinylpyrrolidine

  therefore, styrene, hexane diol diacrylate, dia-

  diethylene glycol crylate, the tetra-diacrylate

  ethylene glycol, and polyethylene glycol diacrylate

  col, and that it is subjected to irradiation at

  medium of ionizing radiation the membrane thus im-

  prégnée for grafting the monomers on the elastomer

  throughout the thickness of the membrane.

  According to a first embodiment of the process, the impregnation of the elastomer membrane is carried out by immersing it in the monomer in the liquid state. Preferably, the monomer is at a temperature ranging from room temperature to 800.degree. C

  and one possibly operates under pressure for the hand-

  keep in the liquid state It is advantageous to operate hot to obtain an impregnation of the membrane on

all its thickness.

  According to a second embodiment of the process of the invention, the impregnation of the elastomer membrane is carried out while maintaining the latter

  in the saturating vapor of the monomer.

  In both cases, to adjust to the desired value the amount of monomers introduced into the membrane and consequently the level of grafted monomers, the duration of impregnation is adjusted as a function of

  the temperature and nature of the monomers used.

  In some cases, after the impres-

  before the irradiation step, the

  membrane impregnated with heat treatment under pres-

  to promote the diffusion of the monomer in

the thickness of the membrane.

  Indeed, to obtain good

  mechanical ticks it is important to maintain homogeneity throughout the thickness of the membrane and thus to achieve grafting throughout its thickness. This hot diffusion treatment consists of

  for example, to maintain the membrane impregnated with

  under a press, at a temperature of 70 to 90 ° C for a duration of about two hours, using

a pressure of 1 M Pa.

  After the impregnation step and possibly

  heat diffusion treatment of the impregnated membrane, the latter is subjected to irradiation by means of ionizing radiation to graft the

  monomers on the elastomer and possibly

  when using polyunsaturated monomers

  by carrying out this grafting and possibly

  this crosslinking throughout the thickness of the mem-

  brane. Ionizing radiation likely

  to be used for this purpose are gamma radiation.

  my and accelerated electron beams, having a

  sufficient energy to cross the membrane.

  For membranes having a thickness of

  2 to 4 mm, an accelerated electron beam having an energy of 1 to 4 MeV, and usually 2 to 3 MeV, is advantageously used. The irradiation dose necessary to ensure the grafting and / or the crosslinking.

  This is usually between 3 and 6 Mrad.

  When the membrane is a flat membrane, the irradiation can be carried out by scrolling

  the membrane laid flat under the electron beam.

  When the membrane has a more complex shape and

  present, for example, in the form of a half-sphere

  re, the irradiation is carried out according to several geo-

  to achieve the best homogeneity of

  In all cases, irradiation is carried out under

  inert atmosphere, for example under azo

you.

  The graft copolymer membranes and possibly

  crosslinked can be obtained after irradiation

  can be used as separating elements in

  hydropneumatic systems for land vehicles

very airy.

  Indeed, these membranes present

  to those which already exist a decrease in the permeability to gases which reaches several tens of% and which is acquired without being diminished to a degree incompatible with the intended use,

their mechanical properties.

  Other features and benefits of

  the invention will appear better on reading the examples

  following elements for preparing separator elements according to the invention, which are given for illustrative purposes.

and not limiting.

  In each of these examples, we control the

  permeability of the separator element obtained by using

  the test subject to the standard

  ISO 2782 1977 (F), the essential characteristics of which

are summarized below -

  A disc 54 mm in diameter, cut from the separator element obtained, is held in a leakproof test cell on one side of the element.

  a relative nitrogen pressure is applied.

  aunt of 2 bars at a temperature of 80, 100 or 1201 C.

  The volume of nitrogen diffused through the element is cal-

  abutted from the displacement measurements Al of a

  drop of non-volatile liquid placed in a capillary

  d with a diameter of 2.9 mm closing the low-

  pressure of the test cell The measurements are ef-

  made for about 300 minutes from the debit

  constant The permeability Q is expressed in m 2 / Pa s se-

  in the formula: Q = AV x e x 1 At X Z AP with AV representing the volume of nitrogen collected in this capillary at the end of time At; e representing the thickness of the element; S representing the section

  of the item under test and LP the pressure

nitrogen.

  The volume of nitrogen AV is equal to Al x nd 2 x 273 with e representing the temperature in

4 E)

Kelvin degrees of the capillary tube.

  In FIGS. 1 to 4, the permeability results obtained in the examples are illustrated by the graphical representation of the displacement Al in FIG.

  cm from the drop of liquid in the capillary depending

  In this way, we obtain lines whose angle α with the abscissa axis is

  representative of the permeability of the element

  The value of the tangent of the angle α decreases with permeability. In these figures, the permeability of a separator element constituted by the same membrane has also been shown by way of comparison.

  elastomer which has not received the graft

of the invention.

  In FIG. 1, the straight lines D 1, D 2, D 3, D 5 and D 7 illustrate the permeabilities obtained at 100 C in Examples 1, 2, 3, 5 and 7 on polyurethane separator elements (Desmopan 385). grafted while curve D illustrates the results obtained

  with a desmopan 385 separator element ungrafted.

  In FIG. 2, the curves D 4, D 5 and D 6 illustrate the permeabilities obtained at 120 ° C. in Examples 4, 5 and 6 on separator elements in grafted Desmopan 385 whereas the curve D 'illustrates the results obtained with a separator element in

Desmopan ungrafted.

  In FIG. 3, the curves D 8 to D 12 illustrate

  the permeabilities obtained at 1000 C in the

  examples 8 to 12 on separating elements in poly-

  urethane (UREPAN) graft according to the invention whereas the straight line D "relates to a separating element in

UREPAN ungrafted.

  In FIG. 4, the lines D 13 to D 16

  shine the permeabilities obtained at 100 C with the grafted polyurethane (ESTANE) separator elements

  whereas the line D "'refers to the separate element

ESTANE ungrafted.

Example 1

A plane membrane of

  x 100 mm and 2.2 mm thick polyurethane

  thane known as Desmopan 385, which has the simplified chemical formula OCN l (-R-NH-C-o- (short chain glycol) -O-CNH-) m

O O

  (-R-NH-C-O- (polyester or polyether) -O-C-NH-) N 3 -NCO

O O

  The membrane is immersed for thirty

  acrylic acid at 21 ° C., and then pressurized at 80 ° C. for two hours under

  a pressure of 1 M Pa It is then irradiated under

  at a dose of 5 Mrad by elec-

trons of 2 Me V.

  The level of grafted monomer (AA) after irradiation

  diation is 9.3% by weight relative to the initial weight

  tial, the thickness of the membrane after treatment is

  2.38 mm Its permeability to nitrogen at 100 C is

  presented by the straight line D 1 in FIG.

  its permeability Qo D was 158 10-18 m 2 / s Pa and after treatment its permeability Q 1 is

  143 10-18 m 2 / s Pa, a gain of -9%.

Example 2

  A membrane is treated with Desmopan 385 identical to

to that of Example 1.

  The membrane is immersed for one hour in ethylene glycol acrylate at 30 ° C. and then for one hour at 50 ° C. The membrane is held for two hours at 80 ° C. and 48 hours at room temperature under a pressure of 1 M Pa. Electron beam irradiation of 2 Me V at a dose of Mrad The level of grafted monomer (AEG) by irradiation is 11% by weight relative to the initial weight of the membrane and the thickness of the membrane is of

2.34 mm.

  Its nitrogen permeability at 100.degree.

  is shown by the line D 2 of FIG. 1 Its permeability Q 2 is 129 10 18 m 2 / s Pa; which represents a

gain of -18.4%.

Example 3

  A membrane is treated with Desmopan 385 identical to

to that of Examples 1 and 2.

  This is placed in saturating steam of

  vinylpyrrolidone for 24 hours at 60 ° C., then irrigated

  radiated under electrons of 2 Me V at a dose of 5 Mrad.

  The amount of monomer grafted after irradiation (OPV 2) is 6.6% by weight relative to the initial weight of the membrane and the thickness of the treated membrane is 2.40 mm.

  Its permeability to nitrogen at 1000 C is

  the line D of Figure 1, its permeability

  Q 3 is 131 10 lc F m 2 / s Pa, which represents a

gain of -17%.

Example 4

  A membrane is treated with Desmopan 385 identical to

  to that of the previous examples.

  This membrane is maintained in the saturated acrylonitrile vapor at 401 ° C. for 3 hours. The membrane wrapped in a thin aluminum foil is then irradiated with an electron beam.

  2 Me V at an irradiation dose of 5 Mrad.

  The amount of monomer grafted after irradiation (AN) is 7% by weight relative to the initial weight of the membrane and the thickness of the treated membrane

is 2.22 mm.

  Its permeability to nitrogen at 1200 ° C. is

  line D 4 of Figure 2 Permeability

  at 1200 C of the untreated membrane Q, (120) was 227 ± 18 m 2 / s Pa and that of the treated membrane Q 4 (120) was 194 10-18 m 2 / s Pa, which represents a

gain of -14.5%.

Example 5

  A membrane is treated with Desmopan 385 identical to

  to that of the previous examples.

  This membrane is maintained in the vapor phase of acrylonitrile at 40 ° C. for 5 hours. The membrane wrapped with a thin aluminum foil is irradiated under an electron beam of 2.5 MeV to

a dose of 5 Mrad.

  The amount of monomer grafted after irradiation (AN) is 12% by weight relative to the initial weight of the membrane and the thickness of the treated membrane

2.32 mm.

  Its permeability to nitrogen at 80 C was 72.10-18 m 2 / s Pa before treatment and it is 37 10-18 m 2 / s Pa after treatment, ie a gain of

-48%.

  At 100 C, its permeability to nitrogen Q 5 (100) is 12210-18 m 2 / s Pa, which represents a gain of

-22.8%.

  At 120 ° C., its permeability to nitrogen is

  presented by line D of FIG. 2 It was 227 10-18 m 2 / s Pa before treatment and it is 1771 c 18 2 177 10-18 m 2 / s Pa after treatment, ie a gain of

-22%.

  The mechanical properties of the membrane before and after treatment are given in the table

1 following.

  Mechanical properties Shore hardness A -hardness DIDC Young modulus at% elongation Young modulus at% elongation Load at break Elongation at break Cold hold: Gehman T 10

Table 1

  : Membrane: before: treatment: (Pts): (Pts): (M Pa): (M Pa):, 6: 7.3: (M Pa): 31.8 36.0

(%): 650 690

(c): Membrane treated 6.1 8.9

3: 42.2

: 665

-37: -32

Example 6

  A membrane is treated with Desmopan 385 identical to

  to that of the previous examples.

  The membrane is kept in the steam

  turante acrylonitrile at 50 C for 1 hour 30 and then

  the membrane wrapped in a thin sheet of aluminum

  nium is irradiated with an accelerated electron beam of 2 MeV at a dose of 5 Mrad. The amount of monomer grafted after irradiation

* (AN) is 15.5% by weight relative to the initial weight

  tial of the membrane and the thickness of the membrane-

treated is 2.53 mm.

  Its permeability to nitrogen at 120 ° C. is

  the line D 6 in Figure 2, its permeability

  Q 6 (120) is 17410-18 m 2 / s Pa, which represents

a gain of -23.3%.

Example 7

  A membrane is treated with Desmopan 385 identical to

  to that of the previous examples.

  The membrane is immersed in hexane diol diacrylate at 19 ° C. for three hours, then it is kept in a press (1 MPa) for two hours.

  hours at 80 C and 48 hours at room temperature.

  Then the membrane is irradiated under an electron beam

  accelerated trons of 2 Me V at a dose of 5 Mrad The level of monomer fixed after irradiation is 4.3% and

  the thickness of the treated membrane is 2.39 mm.

  Its permeability to nitrogen at 100 C is

  sensed by line D 7 of Figure 1; this permea

  Q 7 (100) is 140 10-18 m 2 / s Pa, which represents

has a gain of -11.4%.

Example 8

  It uses a plane membrane of x 100 mm and 2.2 mm thick polyurethane known under the brand UREPAN HU 721, which corresponds to the simplified chemical formula:

NH 10 -CO-NH- (CH 2) 4-N Hn-CO-O-

  This membrane is treated with acrylic acid

  that using the same conditions of impregnation

  and irradiation as in Example 1.

  The results obtained are as follows: Grafted acrylic acid content: 14.3% Thickness of the membrane after treatment: 2.21 mm Permeability with nitrogen at 100 ° C.: FIG. 3, right D

  Permeability before treatment Qo U (100): 186 10-

  m 2 / s Pa Permeability after treatment Q 8 (100): 131 10-18 m 2 / s Pa Gain: -29.6%

Example 9

  A membrane identical to that of Example 8 is immersed in ethylene glycol acrylate (AEG)

at 300 C for one hour.

  The membrane is then held for two hours at 80 ° C. and 48 hours at room temperature.

under a pressure of one ton.

  Irradiation in the absence of air is achieved

  2 Me V electron beam at a dose of Mrad. The results obtained are as follows: Grafted AEG level: 6.6% Thickness of the membrane after treatment: 2.43 mm Nitrogen permeability at 100 C: Figure 3, line D Permeability after treatment Q 9 (100) : 13610 m 2 / s Pa Gain: -27%

Example o 10

  A membrane identical to that of Examples 8 and 9 is treated with vinyl pyrrolidone (OPV 2) in

  according to the technique of Example 3.

  The results obtained are as follows: Grafted OPV 2: 8.1% Thickness of the membrane after treatment: 2.20 mm Permeability to nitrogen at 100 C: Figure 3, right D Permeability after treatment Q 10 (100) : 175 108 m 2 / s Pa Gain: -5.9%

Example 11

  A membrane identical to that of the examples

  8 to 10 is treated as in Example 5.

  The results obtained are as follows: Grafted acrylonitrile level: 10% Thickness of the membrane after treatment: 2.38 mm Nitrogen permeability at 80 C: Membrane before treatment QO (80): 63 10-18 m 2 / s Pa Membrane after treatment Q 1 l (80): 10-18 m 2 / s Pa Gain: -52% Nitrogen permeability at 100 C: Figure 3, curve D Membrane after treatment Q 11 (100): 142 10-18 m 2 / s Pa Gain: -23.7% Mechanical properties: (Table 2)

Table 2

  : Membrane: Pre-treated membrane treatment: Shore hardness A (Pts): 78: 78 Hardness DIDC (Pts): 77: 76 Young's modulus at 100% (M Pa): 6.2: 8.0 Lengthening Load at break (M Pa): 22.8: 24.0 elongation at break (%): 380: 280 350 cold hold: Gehman (C): -28.5: -27 T 10

Example 12

  A membrane identical to that of the examples

  8 and 11 is treated as in Example 7.

  The results obtained are as follows: Fixed hexanedil diacrylate level: 7.9% Thickness of the membrane after treatment: 2.18 mm Permeability to nitrogen at 100 ° C: Figure 3, right D 12 Permeability after treatment Q 12 (100): 123 10-18 m 2 / s Pa Gain: -33.9%

Example 13

  A polyurethane membrane known under the brand name Estane 100 x 100 mm and 2.2 mm thick is treated with acrylic acid according to the conditions

examples 1 and 8.

  The results are as follows: Grafted acrylic acid content: 7.3% Thickness of the membrane after treatment: 2.21 mm Permeability with nitrogen at 100 ° C.: FIG. 4, right D

  Permeability before treatment Q O (100): 149 10-

  m 2 / s Pa Permeability after treatment Q 13 (100): 138 1018 m 2 / s Pa Gain: -7.4%

Example 14

  A membrane identical to that of Example 13 is treated with ethylene glycol acrylate in

  according to the technique of Example 2.

  The results obtained are as follows: Grafted ethylene glycol acrylate content: 7.7% Thickness of the membrane after treatment: 2.2 mm Permeability to nitrogen at 1000 ° C.: FIG. 4, right D% Permeability after treatment Q 14 (100): 121 10 m 2 / s Pa Gain: -18.8%

Example 15

  A membrane identical to that of Examples 13 and 14 is treated with acrylonitrile following the

  method used in Examples 5 and 11.

  The results obtained are as follows: Grafted acrylonitrile level: 15% Permeability thickness Permeability m 2 / s Pa Permeability m 2 / s Pa Permeability Permeability m 2 / s Pa grafted membrane: nitrogen at 800 ° C before treatment 2.25 mm

Q O (80): 4410-18

  after treatment Q 15 (80): 28 10-18 Gain: -36% with nitrogen at 100 C: FIG. 4, line D after treatment Q 15 (100): 125 10 Mechanical properties Gain: -16.1%

: (table 3)

Table 3

  : Membrane: Membrane Before treatment treated Hardness shore A (Pts): 88: 89 hardness DIDC (Pts): 89: 87 Young's modulus at (M Pa): 7.4: 7.4% elongation Young at (M Pa): 12.5: 14.1% elongation Breaking load (M Pa): 24.7: 30.2 Elongation at (%): 520: 560 Breaking strength (C) ): -27.5: -26

Example 16

  A membrane 13 to 15 is treated with the same as that of the examples hexanediol diacrylate following the technique used for Examples 7 and 12.

13256

  The results obtained are as follows: Fixed hexane diol diacrylate content: 3% Thickness of the membrane after treatment: 2.17 mm Permeability with nitrogen at 100 ° C: FIG. 4, right D Permeability after treatment Q 16 (100 ): 130 10-8

2 1

  m 2 / s Pa Gain: -12.7% In the attached table 4, we grouped together the

  results obtained in the examples given above.

  In view of this Table, we see that the best results are obtained when using

  acrylonitrile as a grafting monomer.

T A BL EA U 4

MEMBRANE P A N S TA NE

  rate of: Permeability to nitrogen rate of: Permeability to: monomer a 02 monomer nitrogen Monomer grafted: (en%> <in m: S s Pa x 108> (in%): (en, m 2 / s Pax 105-Lu * * GainGai Q Gain: Q Gain n Treaty 63: 186: 44: 149

*: (<80) :( O 100): (OE 80): 00

  Acrylic acid 14.3 -11 2,% 731874 Ethylene glycol acrylate: 6.6 :: 136 27% 7 ,: 121 18.8% Vinyl pyrrolidone: 8.1: 175 5.9% Acrylonitrile:

: 10: 30 52%: 142 23.7% 3% 2 61

  e c * 15:28 3612161 Hexanediol diacrylate: 7.9: 123 33.9% 3: 130 12.7% Wt.

T A BLEA U -4 (CONTINUED)

  <rate of: Nitrogen permeability in m 2 / s -Pa x 10-18: Mnonomer 81 01 21 M grafted monomer fx O 0010: (in%): Q Gain: Q Gain: Q Gain Untreated: 72: 158: 227 Untreated: (O 080) :( <0100) :( O Acrylic acid: 9, 3 :: 143 9%: Ethylene glycol acrylate: 11: 129 18.4%: Vinyl pyrrolidone 6 , 6: 131 17%: Crylonitrile: 7: 194 14,, 5%

12:37 48%: 122 22.8%: 177 22%

* S 17423.3%

, 5 _ -

  Hexane diol diacrylate 4.3 140 11.4%:

19 2 2513256

Claims (12)

  Separating element, characterized in that it comprises an elastomer membrane grafted with monounsaturated and / or polyunsaturated monomers selected from the group comprising acrylic acid and its   esters, ethylene glycol acrylate, acrylonitrile   vinylpyrrolidone, styrene, hexane diol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, and diacrylate of polyethylene glycol.   Element according to claim 1, characterized   in that the level of monomers grafted is 2   at 30% by weight relative to the weight of elastomer.   3 Element according to any one of   1 and 2, characterized in that the elastomer   re is chosen from the group consisting of polyurethanes   thanes, polychloroprenes, silicones, poly-   ethylene-acrylic mothers such as copolymers   ethylene and methyl acrylate, polyisobutyl   polynorbornenes, polybutadiene-acrylonitrile   nitriles, polybutadiene-styrenes, polybutadiene   dienes, polyisobutylene-isoprenes, polyiso-   prènes, chlorosulphonated polyethylenes, poly   (ethylene-propylene), poly (ethylene-propylene-   diene) and poly-ethylene sulfides.   4 Element according to any one of the   1 to 3, characterized in that the membrane is   polyurethane grafted with acrylonitrile.   Process for preparing a separable element   according to any one of claims 1 to 4,   characterized in that a membrane is impregnated   elastomer of monounsaturated and / or polyunsaturated monomers   selected from the group consisting of acrylic acid 13256   and its esters, ethylene glycol acrylate, acrylonitrile, vinylpyrrolidone, styrene, hexane diol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, and polyethylene glycol diacrylate, and in that one   undergoes irradiation with radiation io-   the membrane so impregnated to graft the monomers onto the elastomer throughout the thickness of the membrane.   Process according to claim 5, characterized   in that the impregnation is carried out by immersing   providing said elastomeric membrane in the monomer the liquid state.   The method of claim 6, wherein   characterized in that the monomer is at a temperature ranging from room temperature to 801 C.   The method of claim 5, wherein   in that the impregnation is carried out by hand   holding said elastomeric membrane in the vapor saturating monomer.   Process according to any one of the   5 to 8, characterized in that before irradiation   The monomer-impregnated elastomer membrane is subjected to heat treatment under pressure to promote diffusion of the monomer through the thickness of the monomer. the membrane.   Process according to any one of   5 to 9, characterized in that the irradiation   This is done by means of an accelerated electron beam of energy between 1 and 4 MeV.   The method of claim 10, wherein   characterized in that the irradiation dose is from 3 to Mrad.   12 Application to the Hybrid Suspension System   dropneumatic for land and air vehicles   the elastomeric separator element according to any one conque of claims 1 to 4.